Syringes are widely used for injecting fluids into a patient's body. Syringes may be used for injecting into a blood vessel, into the skin tissue or into a muscle. Syringes may also be used to withdraw a sample of body fluid, such as amniotic fluid or blood, for example.
Essentially, a syringe consists of a cylindrical barrel with a narrow opening at one end, and a cylindrical plunger that tightly fits inside the barrel. A hollow needle may be fitted to the narrow opening. Raising the plunger in the barrel causes a suction pressure, and if the narrow opening or a hollow needle attached thereto is submerged in a fluid, the fluid is sucked into the barrel. Depressing the plunger causes fluid to be ejected from the syringe. Syringes are often marked with a graduated scale, so that exact quantities of fluid may be sucked in or ejected.
Syringes are available in different sizes. One common size is a 1 ml syringe that is typically marked with a scale into 0.1 ml sections. Each of these is divided into 0.02 ml subsections and such a syringe may be used to inject small doses such as 0.02 ml or 0.1 ml doses.
One application for micro syringes is to inject botulinium toxin or “botox”. Botulinium toxin was first used in medical applications for treating strabismus (“crossed eyes”), a condition in which the eyes are not properly aligned with each other, and blepharospasm, which is an uncontrollable blinking disorder.
Dr. Richard Clark and the husband and wife team of J D and J A Carruthers pioneered use of botulinium toxin for treating wrinkles and frown lines.
In April 2002, the FDA announced regulatory approval of botulinum toxin type A (Botox Cosmetic) to temporarily improve the appearance of glabellar lines, which are the moderate-to-severe frown lines that may appear between the eyebrows. Subsequently, cosmetic use of botulinum toxin type A has become widespread. The results of cosmetic procedures vary, but can last up to eight months.
BTX-A is now a common treatment for muscles affected by the upper motor neuron syndrome (UMNS), such as cerebral palsy, for muscles with an impaired ability to effectively lengthen. Muscles affected by UMNS frequently are limited by weakness, loss of reciprocal inhibition, decreased movement control and hypertonicity (including spasticity). Joint motion may be restricted by severe muscle imbalance related to the syndrome, when some muscles are markedly hypertonic, and lack effective active lengthening. Injecting an overactive muscle to decrease its level of contraction can allow improved reciprocal motion, so improved ability to move and exercise.
BTX-A has also been approved for the treatment of severe primary axillary hyperhidrosis which is an excessive underarm sweating disorder.
Botulinum toxin type B (BTX-B) received FDA approval for treatment of cervical dystonia on Dec. 21, 2000. Trade names for BTX-B are Myobloc in the United States, and Neurobloc in the European Union.
Onabotulinumtoxin A (trade name Botox) received FDA approval for treatment of chronic migraines in 2010. The toxin is injected into the head and neck to treat these chronic headaches. Since then, several randomized control trials have shown botulinum toxin type A to improve headache symptoms and quality of life when used prophylactically
Where the Botulinum toxin is injected into specific muscle tissue, a multiple number of small doses are injected in independent needle insertions into same area of the patient's muscle. The scale of each independent injection can vary from 0.1 ml. to 0.02 ml. the commonly used syringe is a 1 ml. syringe, meaning in some cases up to 50 small injections are drawn from one syringe. The technique that is currently used depends on the operator's skills and expertise. The operator needs to inject the portions by looking at the indication lines on the syringe body, but even so it is difficult to inject precise portions into the muscle. A disadvantage of the technique is that the operator is obliged to keep eye contact with the syringe rather than looking at the patient's skin or muscle while injecting. Furthermore, because of the difficulty to inject accurate doses of such a small size, operators often dilute the concentrated drug with saline and inject larger portions of the diluted drug. This technique improves the ability to inject accurate dosages of the drug but requires the operator to inject a larger quantity of fluid which is fairly quickly dispersed. The amounts injected and the ensuing results may be less than optimal.